At present, LEDs are applied more and more widely, and LED lamps for daily indoor and outdoor lighting are more and more popular. The present LED lighting is increasingly developed towards the high power direction, and the high heat brought by high-power LEDs is an important factor puzzling the popularization of the LEDs. If an LED works at a high temperature for a long term, the service life of the LED could be greatly shortened, the exertion of advantages of the LED could be affected, and even a dead lamp phenomenon could be caused eventually leading to rejection of the lamp. If the lamp can be automatically turned off at overheat, the aforementioned adverse consequences can be avoided. But in some cases, even if the temperature is high, lighting is still needed, and at this moment, if the lamps are turned off, the lighting function cannot be realized, and the service requirement cannot be met.
In addition, in an environment where a plurality of LED lamps are simultaneously used, if the plurality of LED lamps are simultaneously turned on, a switching surge shock is produced, and the voltage instantaneously fluctuates within a large range. Once the instantaneous voltage is overly high, key components in the circuit may be shocked. Once the instantaneous voltage exceeds the bearing capacity of the components, the key components are damaged to cause death and rejection of the LED lamps.